This invention relates to a liquid-cooled internal combustion engine having a cylinder block and a cylinder head, formed with coolant cavities which have inlet and/or return ports which can be connected to the input or output side of a recirculating pump, and a temperature-controlled regulating device for controlling the flow of coolant through the said cavities.
In one such internal combustion engine, for example, the flow of the coolant through the cylinder head is released by a thermostat only when the engine has reached its operating temperature. Because the coolant is not circulated through the cylinder head cavity surrounding the combustion chamber during the warming up phase, rapid heating of this part of the engine occurs, designed to produce optimal operating conditions of the internal combustion engine a short time after starting. On the other hand, with this design since the comparatively cold coolant constantly flows through the cylinder block, particularly after cold starting, only delayed heating of this part of the engine can take place so that considerable friction losses and cold wear in the cylinders occur in these operating conditions.